Project Summary/Abstract The unmet need for effective addiction treatment within the criminal justice system ?represents a significant opportunity to intervene with a high-risk population? according to NIDA's 2016-2020 strategic plan. The plan also encourages the development and evaluation of implementation strategies that address the needs of the criminal justice system. This Mentored Patient-Oriented Research Career Development Award (K23) will prepare the applicant with the skills necessary to launch an independent research program focused examining implementation strategies to support the uptake of evidence-based mental health interventions for incarcerated substance users. The applicant's training goals are as follows: 1) develop expertise in implementation science research methods, 2) increase knowledge relevant to interventions for substance users, and 3) enhance skills necessary for a successful research career. These training goals will be achieved through a combination of mentored research and study, didactic and experiential learning, and intensive externship training. Because severe trauma exposure, substance use, and justice-involvement overwhelmingly co-occur in prison populations, the applicant's research plan will aim to advance knowledge on implementation of a gold-standard psychotherapy for trauma, Cognitive Processing Therapy (CPT), in the prison setting. She will also examine whether prison-delivered CPT reduces drug use, psychiatric symptoms, and recidivism. The three specific aims in this research are: 1) Use formative evaluation to identify factors that may influence implementation and uptake of CPT in prisons, 2) Adapt CPT for incarcerated drug users and develop a facilitation-based implementation guide to support its uptake, and 3) conduct a participant-randomized Hybrid II trial to assess effectiveness and implementation outcomes of CPT with incarcerated drug users. If found to be effective, wide- scale implementation of CPT may improve the health of over 1.7 million incarcerated Americans who have co- occurring substance use and trauma exposure. The work proposed in this application will be conducted at the University of Arkansas for Medical Sciences, a rich context for early stage investigators, under the guidance of mentoring from the following national experts: Drs. JoAnn Kirchner and Geoffrey Curran for implementation science, Dr. Nickolas Zaller for drug use and its overlap with the criminal justice system, and Dr. Debra Kaysen for CPT and its adaptation in low-resource contexts and with substance users. At its conclusion, the applicant will have progressed toward her goal of becoming a criminal justice implementation scientist by 1) advancing foundational knowledge on CPT implementation within the criminal justice system and effectiveness as treatment for addiction and 2) publishing research on application of implementation science in criminal justice settings.